This invention relates to power converters that are controlled by a pulse width modulator. One such converter is a switch-mode power converter.
A typical switch-mode power converter takes a rectified AC signal, steps down the voltage, and delivers a regulated DC signal. A switch controls the conduction period or duty cycle of the converter. Switching, in turn, is controlled based on a signal representative of the output of the converter.
Voltage regulation of the output is typically achieved by pulse width modulating (PWM) the conduction time of the switch (i.e., the period when the switch is closed) while keeping the switching frequency fixed. Regulation has also been achieved by varying the frequency of fixed-width pulses, as well as by various combinations and variations of PWM and frequency variation.